Business
Merge & Dedupe Spreadsheets
Combine up to ten Excel or CSV files into one sheet — columns matched by heading, rows stacked — then remove duplicates on the columns you choose, with every removed row listed by source file and row. Runs in your browser; nothing is uploaded.
Privacy
Your file never leaves your device. It is read and converted by your own browser, so nothing is uploaded, queued or logged — which is what makes this safe for a client’s books.
Tips
- Headings are matched ignoring case, spaces and punctuation, so "E-mail" and "email" are one column, and so are "Phone No." and "phone no" — but "Email Address" and "Mobile" are not. Use the alignment panel to merge the ones that should be one column.
- Choose the key columns carefully. Email alone finds the same person under two spellings of their name; name plus phone finds them under two email addresses. No key at all means only rows identical in every column are duplicates.
- With normalisation on, emails are compared lower-case and phones as digits only, with a leading +91 or 0 dropped — so 098450 12345 and +91 98450 12345 match. Off, the comparison is exact after trimming and case-folding.
- Keep first keeps the row from the earlier file, in the order you added them; keep last keeps the later one. Add the file you trust most first, or last, accordingly.
- Only the first sheet of a workbook is read. If the data is on another tab, move it or save that tab as its own file.
- The Duplicates removed sheet says which kept row each one matched. Check a few before you delete the originals.
Frequently asked questions
What counts as a duplicate?
Two rows whose values in the key columns are equal after trimming and case-folding — and, with normalisation on, after emails are lower-cased and phones reduced to digits. Rows whose key columns are all empty are never treated as duplicates of each other; they are kept and counted.
What if the files have different columns?
The output has every column from every file, in the order they were first seen. A row from a file without a column has that cell empty. Columns that mean the same thing under different headings can be merged into one in the alignment panel before the rows are stacked.
How large a file can it take?
It is limited by the browser’s memory, not by any upload. A few hundred thousand rows across ten files is fine on a laptop; the preview shows the first 25 rows and the download has them all.